The four chords
I | V | vi | IV
Home, the pull, the shadow, the door: the most used progression in pop.
Learn · Understand the neck
Chords from a scale: the chords in a key
Why every key has seven chords and where they come from: stack 3rds on each note of the scale, and major, minor and diminished chords fall out in the same pattern every time. Each with its numeral and its job, sevenths too, and progressions to play, in any key.
Key
Stack the 3rds
Write out a scale twice. Start on any note, then take a note, skip a note, take a note: three notes a 3rd apart, which is a chord. Do it from each of the seven notes and you have the seven chords of the key. They use only the scale’s notes, which is why they sound like they belong together. Press a chord to see where its notes come from.
- C1
- D2
- E3
- F4
- G5
- A6
- B7
- C1
- D2
- E3
- F4
- G5
- A6
- B7
I · C: C, E, G. Its 3rd is a major 3rd (four frets): a major chord. In C major it is home.
The seven chords of C major
Each column is one chord, its root at the bottom. The dots are coloured by what each note is in its own chord, so look at the blue in the middle: a bright blue 3rd is a major chord, a dark one minor; a dark green 5th means diminished. Press one to hear it.
Strummed with the Library’s first shape for each, on your own guitar.
The pattern
IiiiiiIVVvivii°
Every major key runs major, minor, minor, major, major, minor, diminished. Numerals count the chords: capitals for major (I, IV, V), small letters for minor (ii, iii, vi), ° for diminished. Because the pattern never changes, a progression written in numerals works in any key.
What each chord does
Chords in a key have jobs. Home is where a song rests; the pull (V) leans back to it hardest; the door (IV) opens away from home. The colours are Songling’s feelings for each job, the same as on the key and progression pages.
Ihome · major
where the progression comes to rest
iirestless · minor
a minor chord moving on towards the pull
iiihalf-light · minor
between home and the shadow
IVthe door · major
opening away from home
Vthe pull · major
the chord that leans hardest back home
vithe shadow · minor
the major key’s own minor chord
vii°the edge · diminished
tense and unstable, it has to move
Play them
Three progressions in C major, built from nothing but these seven chords. Change the key above and they follow.
Every key
Every key has its own page with the seven chords as Library cards to strum and move along the neck, the notes, progressions and capo shapes.
Look it up
See every key at once on chords in every key, move a song to an easier key with the capo chart, or hear what each chord does in the chord progressions.
Questions
How do you find the chords in a key?
Take the key’s scale and build a chord on each note by stacking every other note: the 1st, 3rd and 5th notes from where you start. In a major key that gives major, minor, minor, major, major, minor and diminished chords.
What are diatonic chords?
The chords built only from the notes of one scale: the seven chords of a key. Chords from outside it (borrowed chords) add colour, but the diatonic seven are the home ground.
What do the Roman numerals mean?
The chord’s place in the key: I is built on the 1st note, V on the 5th. Capitals are major, small letters minor, ° diminished. In C, I–V–vi–IV is C, G, Am, F; in G it is G, D, Em, C.
Why is the seventh chord diminished?
Built on the 7th note of a major scale, its 3rd is minor and its 5th is flat (three frets and then three more), so it is tense and wants to move. Songs often leave it out, or use V7 instead, which contains it.
How do I work out what key a song is in?
List its chords and find the key that holds them all; the chord the song keeps coming home to, often the first and last, is usually the I (or the i, in a minor key).